Project Description The proposed interdisciplinary research project is the first to bridge the theoretical and methodological gaps between pediatric health psychology and behavior genetics to significantly advance our understanding of children's pain. The body of research examining childhood pain points to the likelihood that multiple genetic and environmental factors underlie the development and maintenance of chronic pain in children. Critical questions need to be addressed before efforts at prevention and intervention can have maximum impact. The four aims address four key questions for the field of pain research: 1) genetic and environmental etiology of pain, 2) transmission of pain across generations, 3) the role of environmental risk and protective factors in pain, and in moderating the heritability of pain, and 4) the growth in pain, including the bidirectional relations between pain and general dysregulation across development. Chronic pain is often comorbid with mood disorders, and we examine the extent to which pain and mood, behavioral and physiological dysregulation share a common etiology. To accomplish our aims, we propose to conduct longitudinal follow ups (9, 10 and 11 years of age) of a birth-records-based community sample of 350 pairs of ethnically diverse twin children. Early risk and resilient aspects of the environment have already been well-characterized, including obstetrical complications and neonatal morbidity coded from medical records, and early parenting. The multi-method approach includes objective assessments of pain frequency, intensity, duration, and disability in twin children and their mothers and fathers. Combining these design features exponentially increases the scientific contribution by elucidating processes that will support preventive intervention efforts.